Mechanical power hammer



March 13, 1934. sc wos 1,951,170

MECHANICAL POWER HAMMER Filed Dec. 14, 1932 2 Sheets-Sheet 1 3K 34 54 l I 2132/ 36 AZ" M v W r lllllllllllmlllmlllllllllll March 13, 1934. H. SCHWOB, 1,951,170

MECHANICAL POWER HAMMER Filed Dec. 14, 1932 2 Sheets-Sheet 2 'l'l'n may L fig/d SW W 33 J/MM/w' Ve/y 6:70. 13)

Patented Mar. 13, 1934 STATES PATENT GFFICE 5 An object of my present invention is to provide a mechanical power hammer of simple, durable and inexpensive construction and having features of improvement over and above the mechanical power hammer disclosed in my co-pending application, Serial No. 628,860, filed August 15, 1932.

A further object is to provide an improved type of connection between a driving element and a driven impact element, both of which are reciprocable, the driving element being driven from a source of power and being operative to cause reciprocations of the impact element, the connection between the two being such as to take full advantage of the force of impact for the purpose of performing digging, drilling, tamping, crushing and riveting operations.

More particularly, it is my object to provide a nonmetallic elastic connection between a driving element and a driven impact element so that a permanent unbreakable connection is provided as distinguished from the metallic spring connection in my copending application which was subject to spring breakage because of vibration and consequent crystallization besides undesired bending of the springs which tended to cause them to break.

Still a further object is to provide an improved connection between a rotary element and a reciprocating driving element of a mechanical power hammer comprising a scotch yoke connection and to provide the yoke set atan angle to increase the impact effectiveness of the tool.

Still a further object is to provide a tool which can be driven by electricity and which can take the place of pneumatic hammer tools without the necessity of providing an expensive and cumbersome air compressing outfit for operating the tool.

Still another object is to provide means for rotating the tool to which the impacts. are delivered for drilling operations and the like.

With these and other objects in view my invention consists in the construction, arrangement and combination of the various parts of my device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawings, in which:

Figure 1 is a front elevation partly in section of one form of mechanical power hammer embodying my invention.

Figure 2 is a side elevation of the same showing the lower part in section.

Figure 3 is an enlarged sectional view on the line 3-3 of Figure 2.

Figure 4 is a sectional view showing the parts in a different position from that shown in Figthe connections for the device in Figure 8; and I Figure 11 is a front elevation of a power hammer showing an internal combustion type of motor applied thereto rather than an electric motor.

On the accompanying drawings, I have used the reference numeral 10 to indicate a tubular guide. Within the guide 10, an impact element 12 is reciprocable. For reciprocating the element 12, I provide an electric motor 14.

The motor 14 has thereon, a pinion 16. The

pinion meshes with a gear 18 which has a shaft 20 journalled in a hub 22.

Pivoted on the gear 18 is a block 24. It is adapted to slide longitudinally in a channel guide 26, which is mounted at right angles on a base member 28. The base member reciprocates on a guide 30 which is secured to the tubular guide 10 (see Figure 5). The block 24 travels in a circle and the channel guide 26 travels vertically or longitudinally of the base 28, the elements 24 and 26 thus forming a scotch yoke.

The elements 26 and 28 constitute a driven element driven from the motor 14 and which in turn is adapted to drive the impact element 12. The operative connection between the driving element and the impact element 12 is in the form of an elastic non-metallic link 32.

The link 32, as shown in Figure 1, may be formed of a plurality of rubber bands. The central portion extends through an opening 34 formed in the impact element 12, while the ends encircle spools 36. The spools 36 are mounted on pins 38 extending from the channel guide 26.

It will be obvious that rotary movement of the gear 18 will impart reciprocatory movement to the link 32 and consequently to the impact element 12 longitudinally of the tubular guide 10. The guide 10 is provided with slots through which the link 32 extends, as shown in Figure 3.

The impact element is adapted to strike an anvil element 42 which is loosely secured to the lower end of the tubular guide 10 by a retainer nut 44. The anvil element 42 may be a rivet set as illustrated in Figure 2, or chisels as indicated at 42a and 42b in Figures 8 and 11. The retainer nut 44 being detachable permits of removing the rivet set 42 and substituting therefor any tool suitable for the particularhammering operation to be performed, special tools f or different operations being provided in the same manner as provided for pneumatic hammers.

The action of the link 32 is illustrated by dotted lines in Figure 1 and by full and dotted lines in Figure 4. In the upward travel of the impact element 12, it tends to swing beyond the upper limit of movement or" the guide element '26 because of its inertia. Theelasticity of the link 32 permits such overmovement of the impact element, .for instance to the dotted line position of Figure ,1 in which it will .be noted that the link 32 is bowed upwardly. Both the inertia of the link and the inertia of the impact element 12 cause this. This lengthens the stroke of the impactelement beyond theactual limit of the stroke of the cross head 26 so as to get the additional force imparted to the impactelement 12 because of its ,upward overrun and the consequent in-- crease of tension of the elastic link 36 which tends to bring the impact element downwardly again faster than the travel of the cross head 26 downwardly.

Likewise, at the bottom of the stroke,'the im pact element tends to overrun as shown by solid lines in Figure 4. In overrunning, it strikes the ,anvil .42 or any tool substituted therefor and its movement is arrested by the anvil. Before it is fully arrested, however, the anvil has delivered blow to the work, the impact force of the element 12 being sufiicient to deliver a compara- .tively sharp blow. The proportions of the parts and the weight .of the impact element, of course, would. all be factors entering into the force of the blow and all these factors can be varied for producing hammers of difierent sizes and for different requirements.

By dotted lines in Figure 4, the lowermost po.. sition of the impact element as corresponding to the lowermost position of the cross head 26 is illustrated. The lower end of the impact element is indicated at a and the upper end of the anvil is indicated at b. It is therefore obvious that if the reciprocating cross head is moved very slowly, the impact element will not deliver a .blow to the anvil and will not even touch it. puring rapid reciprocations, however, the inertia of the'impact elementenhanced by its long travel because of overrunning in .the upper end of the tubularguide 10 will cause it to strike the anvil and when fully arrested thereby, the link 32 will i assume the full line position because of its own inertia tending to bend it in this fashion. This bending and that illustrated by dotted lines in Fi ure 1 is a consequence of the structure which causes coil springs to break if they are used between the impact element and the ends of the cross head 26, as shown in my copending appli cation.

It is therefore evident that the link 32 of nonmetallic elastic construction is a decided improvement over the invention shown in my copending application and one which makes for success where the former type was objectionable because of spring breakage.

The link 32 may be laminated as in Figure 1 by being formed of rubber or other non-metallic elastic bands. It may be a solid single rubber band like member of comparatively thick dimensions as shown in Figure 4. It may be formed with a solid center 33 and loop-like ends 35 as shown in Figure 6 if desired, or it may have a solid center as at 33a in Figure 7 with laminated ends 35a.

"With respect to the impact element 12, it will be noted that only a minimum or" the material therein is above the opening 34 and that the maximum portion thereof is below the opening. The purpose of this arrangement is to minimize the weight of material above the opening so that when the impact element is stopped by the anvil element 42 and such material tends to crush the opening due to the momentum of the material, the crushing tendencyis less than when the opening is arranged at the center of the impactelement, asin my copending. application. Thus there is less chance or" breaking the impact element at the corners of the opening thereinand its life is thereby lengthenedconsiderably as compared with the impact element in the application just mentioned.

Various types of drives may be provided between the driving motor and the impact element. Different arrangements can be designed for difiierent sizes and different types of motors. For instance, in Figure a bevel gear drive indicated at 1 7 and 19 is illustrated. The bevel gear 19 carries a roller 25adapted to travel in ayoke element 27. It will be noted in Figures 8 and 11 that the yoke element is inclined. I have found this desirable in order to produce a slightly difierent action of the reciprocating impact element 12. During the last portion of the upward it slows down quickly and then during the first parts of it reciprocatory movements, it starts gradually because of the inclinatien of the element 27.

In other words, besides the ordinary scotch yoke action, the inclination of the yoke element produces a speeding up action adjacent the end of the stroke where ordinarily the action gradually slows down and this tends to impart reciprocation to the impact element as long as possible toward the end of the stroke so as to increase the overruns due to inertia of the impact element. This improves the hammer action to some extent.

In Figure 8, I have illustrated a means for rotating the tool 420. It is carried in a sleeve 46 which has a pair of keyways 48. A plate 50 having "key-s 52 is mounted for rotation on the end of the retainer nut 44. It is secured to a gear 54 which in turn is meshed with a pinion 56. The pinion 56 is mounted on a shaft 58 having a worm gear 60 thereon. The worm gear 60 meshes with a worm 62 on the shaft 20 of the bevel gear 19. Thus during the delivery of impact blows to the tool 42a, the tool is rotated. This is especially ing my mechanical power hammer, I provide a gear 19a,

handle 66 and a push button 68 may be incorporated in the handle for controlling the energizaion of the motor 14 or 14a.

In Figure 11, I have illustrated an internal combustion engine 70 mounted on the hammer structure. A pair'oi handles 72 are substituted for the single handle 66 and this hammer construction is more adaptable for heavy work, the hammer itself being made on a larger scale.

The motor 70 may be belted to the shaft 20 by a normally loose belt 74. A 'belt tightener '76 may be provided for controlling rotation of the shaft 20 relative to the shaft of the engine '70. The degree of tightness of the belt will to some ez'tent regulate the speed of the shaft 20 and thus the hammer action. A control lever '78 is illustrated for controlling the belt tightener '76 and this may be incorporated as a trigger in one of the handles 72 if desired.

Instead of the scotch yoke connection as shown in present application or the connecting rod connection as shown in my copending application, cam arrangements can be provided for reciprocating the cross head. In Figure 9A, for instance, I have shown a driving gear 19a having the shaft 20 located as indicated. The cross head shown at has a guide portion 82 and is provided with a roller an adapted to coact with a cam groove 86. The dash line it indicates a circle ec centric to the shaft 20. A cam groove in this shape could be provided but would produce a uniform rise and fall of the cross head. In order to cause a gradual start and quickened finish of reciprocation of the cross head, the cam groove 86 may be of an irregular shape such as eliptical as shown on the drawings. Thus the portion 1) produces a gradual downward movement of the cross head at the beginning of the downward stroke, while the portion 0 gives a quickened downward movement at the finish of the impact stroke.

The portion 1) provides a gradual movement of the cross head at the start of the retracting reciprocation, while the portion 0 causes a quickened finish to the retracting reciprocation. The of course, must rotate in the proper direction to produce this action, the direction being indicated by the arrow d.

The type of drive between the rotating portion of the device and the reciprocating cross head,

' it will be obvious, can be modified considerably without affecting the novel arrangement of connection between the reciprocating driving element and the reciprocating impact element.

Although I have illustrated the link 32 as having its ends connected with a driving element or cross head and the center of the link as connected with an impact or driven element, it will be obvious that this arrangement can be reversed and yet the same results obtained.

Changes of the characters just mentioned and others can be made without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents, which may be reasonably included within their scope.

I claim as my invention:

1. A device of the class described comprising an impact element guide, an'impact element reciproca le along said guide and means for imparting reciprocation to said impact element comprising a rotating shaft, a cross head reciprocable longitudinally of said guide and parallel with said impact element, a scotch yoke connection between said rotating shaft and said cross head for imparting reciprocations to said cross head, said cross head having rigidly spaced ends on opposite sides of said guide and elastic non-metallic connections between said ends and said impact element and extending slidably through said inipact element.

2. A device of the class described comprising an impact element guide, an impact element reciprocable along said guide and means for imparting reciprocation to said impact element comprising a rotating shaft, a cross head reciprocable longit dinally of said guide and in a path parallel to the path of reciprocation of said impact element, an operative connection between said rotating shaft and said cross head for imparting reciprocations to said cross head, said cross head having rigidly spaced ends on opposite sides of said guide and a non-metallic elastic link between said ends and extending slidably through said impact element.

8. A device of the class described comprising an impact elem nt guide, an impact element reciprocable in a path along said guide and means for imparting reciprocation to said impact element comprising a rotating shaft, a cross head reciprocabie longitudinally of said guide in a path parallel with said first mentioned path, an operative connection between said rotating shaft and said cross head for imparting reciprocations to said cross head, said cross head having ends rigidly spaced relative to each other on opposite sides of said guide and a non metallic elastic laminated link between said ends and extending slidably through said impact element.

4. A device of the class described comprising an impact element guide, an impact element reciprocable along said guide and means for im parting reciprocation to said impact element comprising a rotating shaft, a cross head reciprocable also along said guide, an operative connection between said rotating shaft and said cross head for imparting reciprocations to said cross head, said cross head having ends spaced rigidly from each other on opposite sides of said guide and a non-metallic elastic link between said ends and extending slidably through said impact element, said link having laminated ends and a solid center portion located within said impact element.

5. In a device of the class described, an impact element guide and a cross head guide arranged parallel relative to each other, an impact element and a cross head reciprocable along said guides respectively and an operative connection between said cross head and said impact element comprising a non-metallic elastic link having its central portion slidably connected with said impact element and its ends rigidly spaced and connected with said cross head.

6. In a device of the class described, a pair of parallel guide members, a driving element and a driven impact element reciprocable, one along each of said guide members and an operative connection between said elements comprising a nonmetallic elastic link having its ends rigidly spaced and connected with one of said elements and its central portion slidably extending through the other of said elements.

'7. In a device of the class described, a pair of parallel guide members, a driving element and a driven impact element reciprocable, one along each of said guide members and an operative connection between said elements comprising a non-metallic elastic link having its ends connected with one of said elements and rigidly spaced from each other and its central portion slidably extended through the other of said elements, said link being laminated.

8. In a device of the class described, a pair of parallel guide members, a driving element and a driven impact element reciprocable, one along each of said guide members, said impact element having an opening therethrough adjacent the end opposite the striking end thereof and an operative connection between said elements comprising a non-metallic elastic link having its ends rigidly spaced and connected with said driving element and its central portion slidably extending through said opening in said impact element.

9. In a device of the class described, a pair of parallelly reciprocable elements, one a driving element and the other a driven impact element, one of said elements having an opening therethrough and the other one having rigidly spaced projec-' 

